SRF02 64 GAIN Step

[hg]

Hi ,
I have a question about the 64 Auto. gain step of the SRF02. The minimum gain in these 64 steps, can allow to receive an echo from which distance .

Is there any relation that I can apply between the 64 gain step and the range?

Another question , this Auto. gain step is working by multiplying the received signal by the gain value OR by changing the threshold ???

Thanks Gerry